Did you mean doing this in web view or excel export? Rgds,

I think a general solution is to divide the data into two datastores and display both with Table widgets. The first Table doesn't show headers while the second one does. To divide a pipe to two datastores you could use the Map process like this:

        ->query($sql)
        ->pipe(new Transpose())
        ->pipe(new ColumnRename(array(
            "c0"=>"description",
              "c1"=>"amount"
            )))
        ->saveTo($tmpNode);

        $tmpNode->pipe(new \koolreport\processes\Map(array(
            "{value}" => function($row, $metaData, $index, $mapState) {
                if ($inddex < 5) return $row; // pipe the first 5 rows 
                else return null; // doesn't pipe the rest of rows
            }
        ))
        ->pipe($this->dataStore("First5RowsDatastore"));

        $tmpNode->pipe(new \koolreport\processes\Map(array(
            "{value}" => function($row, $metaData, $index, $mapState) {
                if ($inddex >= 5) return $row; // pipe rows after the first 5 ones
                else return null; // doesn't pipe the first 5 rows
            }
        ))
        ->pipe($this->dataStore("RestOfRowsDatastore"));

Or you could insert the header to the middle of your data:

        ->query($sql)
        ->pipe(new Transpose())
        ->pipe(new ColumnRename(array(
            "c0"=>"description",
              "c1"=>"amount"
            )))
        ->pipe(new \koolreport\processes\Map(array(
            "{value}" => function($row, $metaData, $index, $mapState) {
                $headerRow = [ "description" => "Description", "amount" => "Amount" ];
                if ($index === 5) return [$headerRow, $row];
                else return $row;                
            }
        ))
        ->pipe($this->dataStore("allDataStore"));

Then in your Table widget, use "cssClass"'s "tr" to decide if a row is the inserted header row and add a specific class for it to make its font bold:

Table::create(array(
    "dataSource" => $this->dataStore("allDataStore"),
    "showHeader" => false,
    "cssClass" => array(
        "tr" => function($row) {
            // if $row looks like a header row return some class like "inserted-header-row"
            // else return ""
        }            
    ...
?>
<style>
    tr.inserted-header-row td {
        font-style: bold;
    }
</style>

Pls use excel template export with excel's Table widgets placement instead of export the datastores directly:

https://www.koolreport.com/examples/reports/excel/excel_template/